SPIKE: PARTS: As an assembler, I want to know whether DIY peristaltics are good and which ones are best.

[sparklestheunicorn]

At ~$30/ea in 2023, the three peristaltic pumps are a major part of the cost of the MicroLab. In addition to being costly, they are also relatively limited in terms of the number of vendors selling them to the public. It would be good to look into alternatives and their reliability.

There are a number of 3d-printed peristaltic pump designs out there (one example). An exploration of the various options and tests of their reliability would be helpful in deciding whether we think we want to encourage our users to go with printed pumps, and if so, which ones?

[phaseloop]

Here is the curated list of available pump designs from thingiverse and printables.

Also it's worth considering a different approach - pressing a syringe cylinder to extract given volume of liquid instead of pulling it using pump. The downside of it is the limit of syringe volume while with pump we can connect anything to the input side.

Used assumptions:

• no print-in-place designs, they need good printer tuning and tolerance. Also when they fail you probably need to print a new one from scratch.
• only pumps using steel bearings as pressure elements to have as biggest MTBF as possible and build consistency (i.e pump calibration being a bitch)
• pump form allowing it to mount/adapt it to microlab. No standalone big pumps or weird designs
• stepper motor pumps only, no weird steppers - only Nema 17.
• as simple to print and build as possible - no planetary gears, etc.

Pump designs

Editor's choice!

• https://www.thingiverse.com/thing:4692199

Heavy-duty, well designed pump with adjustable hose tension. Includes source scad files for further modifications (no other design on the list probably does that).

Uses 6 mm tubing.

Other

• https://www.thingiverse.com/thing:4255438

Easy and nice design - uses 3 mm tubing. Pump intake seems to be integrated into housing (??) which seems to be weird.

• https://www.myminifactory.com/object/3d-print-peristaltic-pump-63137

(OG design linked in this issue)

• https://www.printables.com/model/248041-growflow-nema-17-peristaltic-pump

Similar design but uses less popular needle bearing

• https://www.thingiverse.com/thing:1134817

Nice and secure design but needs some minor fixes to tube guide to prevent it from moving and keep the precision.

• https://www.printables.com/model/818373-nema-17-peristaltic-pump-water-pump-measuring-pump

ok-ish but tube seems to not be secured properly and there is a risk it will fall out during operations

• https://www.printables.com/model/129756-peristaltic-pump-nominal-diameter-o8mm-for-fluids-

ok-ish but the bearing mount gives me anxiety and I doubt it will work more than 10 minutes. Someone tried to adapt aluminium pump to 3d printing.

• https://www.thingiverse.com/thing:3346506

Easy and clean design but risk of tube falling out

• https://www.thingiverse.com/thing:3109449

Nice and clean design but bearings are not secured with screws and keeping pressure between pump rotor and motor shaft is the single point of failure.

[sparklestheunicorn]

Thanks @phaseloop! We're running this by some of the CAD design folks.

[phaseloop]

I have a pretty long and solid experience in FreeCAD - I would love to join discussions if that's possible.

[sparklestheunicorn]

@phaseloop please drop us an email at volunteerⒶfourthievesvinegar.org and we'll put you in touch.